1. Technical Field
The present disclosure relates to a light emitting diode (LED) and a method for manufacturing the same and, more particularly, to an LED having spiral bonding wires and a method for manufacturing the LED.
2. Description of Related Art
LEDs have been available since the early 1960's. Because of the relatively high light-emitting efficiency of LEDs, nowadays LED usage has been increased in popularity in a variety of applications, e.g., residential, traffic, commercial, industrial settings. A typical LED generally includes a base, an LED die bonded on the base and an encapsulant enveloping the LED die. For supplying power into the LED die, two arced bonding wires are provided to connect two opposite electrodes of the LED die to metal patterns which have been printed on the base, or metal blocks which have been embedded within the base beforehand. The two bonding wires are sealed by the encapsulant in a tight manner, avoiding oxidation or collision.
In order to ensure a good electrical connection between the LED die and the base, the bonding wire is generally made from gold which has an electrical conduction capability better than other metals, such as copper or iron. Due to being made from such a precious material, the bonding wire is often manufactured relatively thin for reducing the cost. Further, a light-extracting efficacy of the LED also requires the bonding wire to be thin enough, since a thick bonding wire may block a large amount of light emitted from the LED die and thus significantly reduce the whole light output of the LED. Accordingly, a diameter of the bonding wire well known in the relevant art is chosen from 1.0˜1.5 mil (one thousandth of an inch).
For allowing as much light out of the LED as possible, the encapsulant is often made of transparent material such as glass, epoxy, silicon or the like, which have an Coefficient of Thermal Expansion (CTE) far larger than that of the gold. When the LED is used under a relatively severe environment, for example, a winter having a temperature below −20°, the encapsulant shrink much more dramatically than the bonding wire. Such difference between the shrinking degrees of the encapsulant and the bonding wire causes the bonding wire to be deformed by the encapsulant, resulting in a risk of rupture of the bonding wire due to a poor stress-resisting capability thereof.
In addition, at the instantaneous time when the LED is activated, a current which varies abruptly from zero to a target value, is produced. Such abruptly varied current directly input to the LED die from the bonding wire may cause an undesirable damage to the LED die.
What is needed, therefore, is an LED which can overcome the above-mentioned disadvantages.